1. The Humoral (B cell) Immune Response

4. Linked Recognition

6. Th2 focus their activating cytokines… (Talin binds to actin microfilaments)

7. Antibody isotype switching:

8. Switch transcripts produced on both chromosomes

9. Where do activated B cells and activated helper T cells get together? (trapping) Freq of lympho’s specific for given Ag is 1/1,000,000

10. Some B cells in the primary focus become plasma cells

11. Other B cells form germinal centers Somatic hypermut’n Affinity maturation Isotype switching

13. FDCs attract B cells to germinal centers

14. B cells undergo somatic hypermutation, selection (+ and -) 1 bp change per 1000 bp per cell division V regions 360 bp ¾ of changes is an altered aa ½ of B cells gets changed BCR

15. B cell survival in Germinal Centers Cross-linking of BCRs by Ag –Ag on FDCs??? –Pathogens multiplying in lymphoid tissue??? CD40 ligation by T cell CD40L Other signals? –Eg. TNF family cytokines

16. Thymus-independent 1 Ags (TI-1) Induce all B cell division Called B cell mitogens Eg. LPS Unable to induce isotype switching(?), affinity maturation, or memory cells

17. TI-2 Ags Activate only mature B cells Repeating epitopes IgM, sometimes IgG Eg. Bacterial capsular polysaccharides, pyogenic bacteria

21. Transcytosis of IgA Gut, lungs, tears, saliva, mammary Poly-Ig Rc Protection of epithelial surfaces

22. IgG and IgA can inhibit viral infectivity

24. IgM has two conformations

29. Ag-bound Ab binds FcRc with high avidity

30. Fc and C3b Rc’s on phagocytes

31. Schistomsome larva attacked by eosinophils

32. ADCC = antibody- dependent cell- mediated cytotoxicity

33. IgE pre-loaded on mast cells Cross-linking causes mediator release Prostaglandin D2, leukotriene C4, TNF-alpha